In several applications for scanning television systems, there is need for an apparatus or method which controls the portrayal of movement.
Such a requirement exists, for example in the area of video data transmission where typically only limited bandwidth is available for the amount of data required to be transmitted from one point to another, for example via telephone land lines. To prevent overloading of the transmission medium, it is necessary to transmit data at a slower rate than it is actually being produced, so due to the length of time required to transmit the data, this precludes real time transmission of picture information which is a disadvantage especially where this has content movement.